The impact of face-to-face social exclusion on university students’ interpersonal cooperation behavior: a hyperscanning study based on fNIRS

Background – Most studies on social exclusion adopt virtual paradigms focusing on unilateral responses, while neglecting real-world face-to-face interaction and its neural basis. Functional near-infrared spectroscopy (fNIRS) hyperscanning allows recording of interpersonal neural synchronization (INS) during dyadic interaction, providing a novel approach for investigating interpersonal cooperation. Methods – This study recruited 24 dyads of college students randomly assigned to social exclusion and inclusion groups. Using fNIRS hyperscanning combined with a face-to-face rejection paradigm and the Prisoner’s Dilemma task, we examined subjective experience, behavior, and INS. Results – (1) The exclusion group reported lower intimacy, trust, belonging need and state self-esteem than the inclusion group. (2) Only defection decision reaction time was faster in the exclusion group, with no group differences in overall cooperation and defection rates, indicating exclusion primarily accelerates defection. (3) INS showed channel-specific differences: the exclusion group had weaker right orbitofrontal INS during cooperation and stronger left dorsolateral prefrontal INS during defection. (4) Cooperation reaction time negatively correlated with trust, while defection efficiency positively correlated with left frontopolar INS. (5) State self-esteem partially mediated the link between social exclusion and defection reaction time. Conclusion – From an integrated psychological–behavioral–neural perspective, this study confirms that face-to-face social exclusion accelerates defection decisions by impairing subjective interpersonal experience, altering prefrontal INS, and through the mediating effect of subjective feelings. These findings provide empirical evidence for understanding the mechanisms underlying campus social exclusion.